Question 337187
How far can airplane fly from its base, and yet return within 3 hours,
 if its outgoing speed is 600 kilometers per hour and its returning speed is 400 kilometers per hour?
:
let d = the one-way distance
:
Write a time equation, Time = dist/speed
out time + return time = 3 hrs
{{{d/600}}} + {{{d/400}}} = 3
multiply by 1200 to get rid of the denominators, results
2d + 3d = 3(1200)
5d = 3600
d = {{{3600/5}}}
d = 720 mi the plane can fly from it's base and return
:
:
Check by finding the times
720/600 = 1.2 hrs
720/400 = 1.8 hrs
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total time: 3 hrs; confirms our solution of 720 mi